Rating is a must for builds. =P 8/10
Idea is unique. I like. Can we rate? It looks awesome. I like the way you used the trawlers.
This.
Except, you can spawn kill with the team spawning outside. You can just get in a trawler and do a driveby to the enemy team. I'd make it so they spawn inside.
I hope you don't care about this but, your sewer thing gave me an idea to make a sewer zombiesurvival, is that ok?